Answer:
option the correct is B
Explanation:
Let's analyze the different options, for a closed system
- an internal reaction changes the system, but does not affect the surrounding environment
- Heat, is a means of transfer that occurs when two bodies are in contact, one of the body can be a closed system since the only thing that happens is thermal transfer, without movement of the system itself. This is the correct result.
- Work implies a movement whereby the system must be mobile, it is not an option
- Pressure change. change in the system, but does not affect the environment
- Mass transfer is not possible in a closed system
After analyzing each option the correct one in B
B) Same magnetic poles attract, while different magnetic poles attract.
C) Opposite magnetic poles attract, while like magnetic poles repel.
D) Opposite magnetic poles repel, while like magnetic poles attract.
The statement about magnetic poles, " Opposite magnetic poles attract, while like magnetic poles repel" is accurate. Hence, Option A is the correct answer.
A Bar magnet has two poles i.e., the north pole and the south pole. The bar magnet has only two sides, the opposite poles doesn't repel each other but attracts each other while same pole repels one another.
The interaction between the magnets, the magnetic materials and all the charges is that the south magnetic pole attracts the north pole of another magnet.
When we consider the given options, As the same magnetic poles repels, Option A , B and D are wrong.
The statement about Magnetic poles, "Opposite magnetic poles attract, while like magnetic poles repel" is the correct statement.
Hence, Option C is the correct answer.
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C) Opposite magnetic poles attract, while like magnetic poles repel.
"The equation can be used to calculate the power absorbed by any surface" statement concerning the Stefan-Boltzmann equation is correct.
Answer: Option A
Explanation:
According to Stefan Boltzmann equation, the power radiated by black body radiation source is directly proportionate to the fourth power of temperature of the source. So the radiation transferred is absorbed by another surface and that absorbed power will also be equal to the fourth power of the temperature. So the equation describes the relation of net radiation loss with the change in temperature from hotter temperature to cooler temperature surface.
So this law is application for calculating power absorbed by any surface.
Answer:
It can apply a greater output force over a greater distance compared to the input force and distance.
Explanation:
A machine helps to multiply force input and makes it easier to do work. Simple and complex machines are need to make work easier.
The statement describes how a machine can help make work easier, (c) It can apply a greater output force over a greater distance compared to the input force and distance is correct option.
A machine is a device designed to perform a specific task or work by using mechanical, electrical, or other forms of energy. Machines are created to make tasks easier, more efficient, or possible to accomplish that would be difficult or impossible to achieve using human effort alone.
They can range from simple tools like levers and pulleys to complex systems like engines and computers. Machines typically involve the conversion of input energy (such as human effort or electricity) into some form of output energy (such as mechanical motion or computation) to achieve a desired result.
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Answer:
D. 39 N m
Explanation:
m = mass of the weight used in crossfit workout = 7.0 kg
Force due to the weight used is given as
F = mg
F = (7.0) (9.8)
F = 68.6 N
d = distance of point of action of weight from shoulder joint = 0.57 m
τ = Torque about the shoulder joint due to the weight
Torque about the shoulder joint due to the weight is given as
τ = F d
Inserting the values
τ = (68.6) (0.57)
τ = 39 Nm
Answer:
The spring constant k is
Solution:
As per the question:
Length of the solid cylinder, L = 500 mm =
Diameter pf the cylinder, D = 2 cm = 0.02 m
As the radius is half the diameter,
Radius, R = 1 cm = 0.01 m
Young's Modulus, E = 17.4 GPa =
Now,
The relation between spring constant, k and Young's modulus:
where
A = Area
Area of solid cylinder, A =
k =
Young's modulus, E is the ratio of stress and strain
And
Stress =
Strain =
Also
Force on a spring is - kL
Therefore, we utilized these relations in calculating the spring constant.